Experimental investigation of different fluid flow profiles in a rotary multi-bed active magnetic regenerator device

Fortkamp, Fábio P.; Eriksen, Dan; Engelbrecht, Kurt; Lozano, Jaime; Barbosa, Jader R.

doi:10.1016/j.ijrefrig.2018.04.019

Cited by 41 publications

(20 citation statements)

References 21 publications

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“…Eq. (12)]. This increases the heat transfer rate, as previously explained-outweighing the effects of the magnetic field.…”

Section: Comparison Of Instantaneous and Rectified Cosine Profiles Usmentioning

confidence: 64%

“…Fluid flow profiles can be more easily investigated experimentally, as no changes in the fluid flow hardware are generally required, provided that a reliable and flexible valving system is in place. In particular, the effect of the duration of the fluid blows has been extensively investigated [10][11][12]. There appears to be a consensus in the literature that the cooling capacity of magnetic refrigerators can be increased by displacing the fluid during periods where the magnetic field is at its extreme values.…”

Section: Introductionmentioning

confidence: 99%

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Numerical analysis of the influence of magnetic field waveforms on the performance of active magnetic regenerators

Fortkamp

Lang

Lozano

et al. 2020

J Braz. Soc. Mech. Sci. Eng.

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Magnetic cooling is an alternative to vapor compression that does not rely on the use of hazardous substances. The refrigerant is a solid material which reacts to oscillations in magnetic field by changing its temperature (the magnetocaloric effect). In active magnetic regenerators, the magnetocaloric material arranged as a porous medium is subjected to an oscillating fluid flow to allow heat transfer from a cold source to a hot sink in a thermodynamic cooling cycle. Although the literature is abundant with studies on the influence of the fluid flow waveform on magnetic refrigeration devices, the influence of the magnetic field waveform has been much less investigated. In this work, we make use of an active magnetic regenerator numerical model with different mathematically defined waveforms to determine which operating parameters yield the highest values of cooling capacity and coefficient of performance for a specific set of operating conditions. The results show that the best performance is achieved when the magnetic field is kept constant for the same time duration of the fluid flow through the magnetized material, and the transition times between the high and low levels of the magnetic field should be as short as possible.

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“…Eq. (12)]. This increases the heat transfer rate, as previously explained-outweighing the effects of the magnetic field.…”

Section: Comparison Of Instantaneous and Rectified Cosine Profiles Usmentioning

confidence: 64%

Section: Introductionmentioning

confidence: 99%

Numerical analysis of the influence of magnetic field waveforms on the performance of active magnetic regenerators

Fortkamp

Lang

Lozano

et al. 2020

J Braz. Soc. Mech. Sci. Eng.

Self Cite

View full text Add to dashboard Cite

show abstract

“…Although the related prototypes already show the features required for practical applications, issues remain that make them still not competitive from a commercial point of view . In particular, complex hydraulic systems are required since a fluid needs to be used as heat exchanger, which can result in complex behaviors, such as different flow profiles . Nonlinear thermal components and thermal switches are alternatives to the use of fluids and, in principle, more efficient in directing the heat flow .…”

Section: Introductionmentioning

confidence: 99%

“…15 In particular, complex hydraulic systems are required since a fluid needs to be used as heat exchanger, which can result in complex behaviors, such as different flow profiles. 16 Nonlinear thermal components and thermal switches are alternatives to the use of fluids and, in principle, more efficient in directing the heat flow. 17 The main barrier is the small number of relevant structures that have so far been developed.…”

Section: Introductionmentioning

confidence: 99%

Enhancing the temperature span of thermal switch-based solid state magnetic refrigerators with field sweeping

et al. 2018

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Summary Magnetocaloric refrigeration has been pointed out as the most promising alternative to the ubiquitous vapor‐compression refrigeration technology due to its high coefficient of performance. Nevertheless, the use of hydraulic components in current devices is, among other reasons, hindering their commercial widespread. Solid state thermally switchable components are alternatives to the use of fluids. Since current developed structures are not ideal, the refrigerator operation design must be optimized to reduce their strict requirements. Active magnetic regeneration in fully solid state systems has been recently shown to be possible by moving the magnetic field gradually at constant speed, i.e., in several isochronal steps. Here, we investigate the implications of different operating modes on the temperature span, where the motion of the magnetic field includes acceleration and deceleration. When the magnetic field is either applied in a single step or from the cold to the hot reservoirs with linear or decelerated motion and is removed with acceleration motion from the hot to the cold reservoirs, the resulted temperature span increases up to 20%. The implications of each operating mode on the optimum frequency is discussed.

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“…Fortkamp et al achieved an efficiency of 19% in 2018 with their AMR system, at a cooling power of 80 W, a cycle frequency of 1 Hz and a temperature span of 10.5 K (ref. 24 ).…”

mentioning

confidence: 99%

Active magnetocaloric heat pipes provide enhanced specific power of caloric refrigeration

et al. 2020

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Today almost all refrigeration systems are based on compressors, which often require harmful refrigerants and typically reach 50% of the Carnot efficiency. Caloric cooling systems do not need any detrimental fluids and are expected to reach 60–70% of the Carnot limit. Current caloric systems utilise the active magnetocaloric regeneration principle and are quite cost-intensive, as it is challenging to achieve large cycle frequencies and thus high specific cooling powers with this principle. In this work, we present an alternative solution where the heat transfer from the heat exchangers to the caloric material is predicated on condensation and evaporation of a heat transfer fluid. Using thermal diodes, a directed heat flow is generated. Thereby we were able to build a cooling unit achieving a specific cooling power of 12.5 W g−1 at a cycle frequency of 20 Hz, which is one order of magnitude larger than the state-of-the-art.

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Experimental investigation of different fluid flow profiles in a rotary multi-bed active magnetic regenerator device

Cited by 41 publications

References 21 publications

Numerical analysis of the influence of magnetic field waveforms on the performance of active magnetic regenerators

Numerical analysis of the influence of magnetic field waveforms on the performance of active magnetic regenerators

Enhancing the temperature span of thermal switch-based solid state magnetic refrigerators with field sweeping

Active magnetocaloric heat pipes provide enhanced specific power of caloric refrigeration

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